3/49+5/7+4/49=3/49+35/49+4/49=42/49=6/7;
1) 3/49+4/49=7/49=1/7
2) 5/7+1/7=6/7
1/12+1/18+1/12=3/36+2/36+3/36=8/36=2/9
1) 1/12+1/12=2/12=1/6
2) 1/6+1/18=3/18+1/18=4/18=2/9
3/49+5/7+4/49=3/49+35/49+4/49=42/49=6/7;
1) 3/49+4/49=7/49=1/7
2) 5/7+1/7=6/7
1/12+1/18+1/12=3/36+2/36+3/36=8/36=2/9
1) 1/12+1/12=2/12=1/6
2) 1/6+1/18=3/18+1/18=4/18=2/9